During the past decade, research on primary liver cancers has particularly highlighted the uncommon plasticity of differentiated parenchymal liver cells (that is, hepatocytes and cholangiocytes (also known as biliary epithelial cells)), the role of liver progenitor cells in malignant transformation, the importance of the tumour microenvironment and the molecular complexity of liver tumours. Whereas other reviews have focused on the landscape of genetic alterations that promote development and progression of primary liver cancers and the role of the tumour microenvironment, the crucial importance of the cellular origin of liver cancer has been much less explored. Therefore, in this Review, we emphasize the importance and complexity of the cellular origin in tumour initiation and progression, and attempt to integrate this aspect with recent discoveries in tumour genomics and the contribution of the disrupted hepatic microenvironment to liver carcinogenesis.